The first heart sound "lubb" (or S1) corresponds to AV valves closing. The second heart sound "dubb" (or S2) corresponds to the closing of semilunar valves closing.
The closing of these valves are so forceful that you can hear these when you are listening to heart beats of a person/patient and this is what we refer to when we are listening to someones heart beat!
Lecture 6: Cardiac Cycle Conduction
Friday 5/17
Pre-Class SlidesDownload Pre-Class Slides
Take notes with me using this handoutDownload Take notes with me using this handout
Lecture 6 (5/17) Exit Ticket (opens when I open it during class!)
Post-class slidesDownload Post-class slides
RecordingLinks to an external site.
This is actually a really nice summary of the whole cardiovascular section we'll cover over the next few weeks. For pre-nursing folks, this is actually put together for their Associate degree in nursing (so this stuff is quite relevant!). I'll leave this here in case folks like a one-stop resource of helpful diagrams & text. Otherwise feel-free to review lecture recordings & pre-class videos: https://www.austincc.edu/apreview/PhysText/Cardiac.htmlLinks to an external site.
Lecture 10 handout Key (will post at the end of the week :) have some folks making up the lecture)
Guiding Questions:
1. Lay out the steps of myocardial cell contraction. Describe carefully what happens in each step.
What is the Ca2+ spark (rush of calcium into the cell)? Where does the Ca2+ come from?
Lay out the steps that lead to relaxation of the myocardial cell after contraction.
How is Ca2+ removed in a contractile myocardial cell?
3. What is the resting membrane potential of a contractile myocardial cell?
What is the trigger for the action potential in contractile myocardial cells? What is the source of that stimulus?
What type of channel activity results in the rising phase, plateau phase and falling phase of the action potential? What is the trigger for each of these types of channel activity?
4. Why is the refractory period in contractile cells so much longer than that in skeletal muscle cells? (covered in post-class week 6, not lecture)
How does the refractory period for myocardial cells prevent summation of force in these cells*****
What would the impact of summation be if it could happen in these cells? Where does the Ca2+ come from to lengthen the refractory period so much? ****These questions will actually be answered during your pre-class week 7! Feel free to skip for now and make sure they are answered by next week!
5. Describe the origin of the pacemaker potential found in autorhythmic cells.
How does the pacemaker potential trigger the rising phase in autorhythmic cells?
What causes the falling phase in autorhythmic cells?
Compare and contrast the rising phase of the autorhythmic cells with the rising phase of the contractile cells, the rising phase in skeletal muscles and the rising phase in neurons.
6. How do action potentials in autorhythmic cells translate to the contraction of the contractile cells?
. What is the function of the cardiovascular system? Give some examples of materials transported by the system.
Describe the organization, pattern of blood flow and the major function of the cardiovascular system using the following terms: heart, arteries, capillaries, and veins.
Describe the structure of the heart and pattern of blood flow through the heart using the following terms: atria, ventricles, septum, vena cava, aorta, pulmonary veins, pulmonary arteries, AV valves, papillary muscle*, chordae tendineae*, semilunar valves.
What is the function of the valves in the heart? Where does the energy come from to open and close the valves? (*covered in lab Week 6)
2. What is the importance of the gap junctions that connect the autorhythmic cells with the contractile cells?
Outline the steps of the intrinsic conducting system and associate them with the steps of the cardiac cycle.
Describe how the SA node controls heart rate. What would happen when the SA node is damaged?
Explain how heart rate is controlled by the parasympathetic system and the sympathetic system. Be sure to discuss the intrinsic heart rate, the neurotransmitters and receptors that operate during control of heart rate
3. Define the terms systole and diastole in terms of the cardiovascular system.****
Explain how pressure gradients drive blood flow in the cardiovascular system. Identify the location of high pressure and low pressure during systole and diastole.*** these questions will be covered next Tuesday's lecture
When I teach this in person, I like to make an analogy between pacemaker cells, contractile cells, and the autonomic nervous system (ANS). Remember that the ANS is divided into sympathetic (speeds up heart rate) and parasympathetic (slows down heart rate).
Consider how lights can be turned on/off and that some have a dimmer switch:
I would argue that each component: pacemaker, contractile cells and autonomic nervous system match the way this lighting system works. Check your understanding by matching the terms below.
How are contractile and pacemaker cells connected? Select all
How does the heart pump? How does it know when to beat?